Development of antileishmanial lipid nanocomplexes.

Visceral leishmaniasis is a life-threatening disease that affects nearly a million people every year. The emergence of Leishmania strains resistant to existing drugs complicates its treatment. The purpose of this study was to develop a new lipid formulation based on nanocochleates combining two active drugs: Amphotericin B (AmB) and Miltefosine (HePC). Nanocochleates composed of dioleoylphosphatidylserine (DOPS) and Cholesterol (Cho) and Ca(2+), in which HePC and AmB were incorporated, were prepared. Properties such as particle size, zeta potential, drug payload, in-vitro drug release and storage stability were investigated. Moreover, in-vitro stability in gastrointestinal fluid was performed in view of an oral administration. AmB-HePC-loaded nanocochleates with a mean particle size of 250 ± 2 nm were obtained. The particles displayed a narrow size distribution and a drug payload of 29.9 ± 0.5 mg/g for AmB, and 14.0 ± 0.9 mg/g for HePC. Drug release occurred preferentially in intestinal medium containing bile salts. Therefore, AmB-HePC-loaded nanocochleates could be a promising oral delivery system for the treatment of visceral leishmaniasis.

Beads made of α-cyclodextrin and soybean oil: the drying method influences bead properties and drug release.

Freeze-dried beads made of α-cyclodextrin and soybean oil were reported previously as an efficient system for the oral delivery of lipophilic drugs. In the present study, oven-drying was evaluated as another method for drying beads. Oven-drying was optimised and the properties of the resulting beads were assessed. The behavior of oven-dried beads and the release of indomethacin from these beads were evaluated in vitro in simulated gastrointestinal fluids and compared with those of freeze-dried beads. The stability of freeze-dried and oven-dried unloaded beads stored at 25°C for 12 months and at 40°C for 6 months in closed and open vials was also studied by different techniques. An oven-drying time of 6 hours at 25°C was chosen as optimal conditions. Oven-dried beads exhibited a sticky texture making them difficult to handle. They were harder, less fragile and smaller than the freeze-dried ones. The characteristics of oven-dried beads make them more resistant in vitro even in media containing bile salt. The rate of indomethacin release from oven-dried beads was much slower than that from the freeze-dried ones. Whatever the drying method, beads must be stored at room temperature protected from humidity. However, no products of oil degradation were detected with both kinds of beads. This work clearly emphasized that the drying method of the beads had a strong influence on their properties, behavior in simulated gastrointestinal fluids and drug release.

Formulations based on alpha cyclodextrin and soybean oil: an approach to modulate the oral release of lipophilic drugs.

The purpose of this work was to investigate the potential of α-cyclodextrin combined to soybean oil-based formulations to modulate the release of a model drug, indomethacin. Dry emulsion, naked and coated beads were prepared from the same initial formulation using the same manufacturing process. Dry emulsion was selected to accelerate drug release while beads coated with α-cyclodextrin were designed to sustain it. Indomethacin-loaded systems were prepared, characterised and evaluated in vitro. Pharmacokinetic studies were performed in fasted and fed rats. The presence of the α-cyclodextrin coat was confirmed by confocal microscopy, and an increase of the mass and diameter of the beads. The layer of α-cyclodextrin improved their resistance in simulated gastro-intestinal fluids. In vitro, the dissolution of indomethacin was slower with coated beads than with emulsion and naked beads. Lipid-based formulations showed an increase of relative bioavailability of IND versus Indocid®. Whatever the formulation, greater and faster release of indomethacin was noticed in sodium taurocholate-rich medium and in fed rats. Compared to naked beads, an increased Cp(max) with a shorter T(max) was observed with the emulsion while T(max) and MRT were increased and Cp(max) reduced with the coated beads. Interestingly, formulations based on alpha cyclodextrin and soybean oil can modify the release of a lipophilic drug depending on the system formed.

Beads made of cyclodextrin and oil for the oral delivery of lipophilic drugs: in vitro studies in simulated gastro-intestinal fluids.

The aim of this work was to investigate the stability in vitro, in simulated gastro-intestinal fluids, of beads, made of α-cyclodextrin and soybean oil, and to study the release of progesterone, a model of lipophilic drug. This was evaluated over time by the monitoring of the proportion of intact beads, their volume and the percentage of progesterone dissolved. Their incubation in the simulated gastric fluid provoked a moderate reduction of their number (20%) and a decrease of their volume (50%) after 55 min. Whatever the intestinal medium subsequently introduced, bead number and volume decreased more until bead disintegration that appeared faster in sodium taurocholate rich-medium. In such fluid, the amount of progesterone dissolved increased rapidly between 65 and 180 min, with both beads and emulsion to be equal after 85 min. With soft capsules, the increase was more gradual. In sodium taurocholate free-medium, more progesterone was dissolved from the emulsion than from beads or soft capsules. The release of progesterone from beads resulted from the erosion of their matrix and its partition equilibrium between oily micro-droplets and aqueous phase. The original structure of beads confers to this multiparticulate system interesting properties for the oral delivery of lipophilic drugs.

Transmembrane diffusion of gemcitabine by a nanoparticulate squalenoyl prodrug: an original drug delivery pathway.

We have designed an amphiphilic prodrug of gemcitabine (dFdC) by its covalent coupling to a derivative of squalene, a natural lipid. The resulting bioconjugate self-assembled spontaneously in water as nanoparticles that displayed a promising in vivo anticancer activity. The aim of the present study was to provide further insight into the in vitro subcellular localization and on the metabolization pathway of the prodrug. Cells treated with radiolabelled squalenoyl gemcitabine (SQdFdC) were studied by differential detergent permeation, and microautography coupled to fluorescent immunolabeling and confocal microscopy. This revealed that the bioconjugate accumulated within cellular membranes, especially in those of the endoplasmic reticulum. Radio-chromatography analysis proved that SQdFdC delivered dFdC directly in the cell cytoplasm. Mass spectrometry studies confirmed that gemcitabine was then either converted into its biologically active triphosphate metabolite or exported from the cells through membrane transporters. To our knowledge, this is the first description of such an intracellular drug delivery pathway. In vitro cytotoxicity assays revealed that SQdFdC was more active than dFdC on a transporter-deficient human resistant leukemia model, which was explained by the subcellular distribution of the drugs and their metabolites. The squalenoylation drug delivery strategy might, therefore, dramatically improve the efficacy of gemcitabine on transporter-deficient resistant cancer in the clinical context.

Thiol functionalized polymethacrylic acid-based hydrogel microparticles for oral insulin delivery.

In the present study thiol functionalized polymethacrylic acid-polyethylene glycol-chitosan (PCP)-based hydrogel microparticles were utilized to develop an oral insulin delivery system. Thiol modification was achieved by grafting cysteine to the activated surface carboxyl groups of PCP hydrogels (Cys-PCP). Swelling and insulin loading/release experiments were conducted on these particles. The ability of these particles to inhibit protease enzymes was evaluated under in vitro experimental conditions. Insulin transport experiments were performed on Caco-2 cell monolayers and excised intestinal tissue with an Ussing chamber set-up. Finally, the efficacy of insulin-loaded particles in reducing the blood glucose level in streptozotocin-induced diabetic rats was investigated. Thiolated hydrogel microparticles showed less swelling and had a lower insulin encapsulation efficiency as compared with unmodified PCP particles. PCP and Cys-PCP microparticles were able to inhibit protease enzymes under in vitro conditions. Thiolation was an effective strategy to improve insulin absorption across Caco-2 cell monolayers, however, the effect was reduced in the experiments using excised rat intestinal tissue. Nevertheless, functionalized microparticles were more effective in eliciting a pharmacological response in diabetic animal, as compared with unmodified PCP microparticles. From these studies thiolation of hydrogel microparticles seems to be a promising approach to improve oral delivery of proteins/peptides.